Abstract

[first paragraph]
How a growing world population
can sustain itself on
Planet Earth has been the
focus of much research.
Norman Borlaug (1), the ‘‘father of the
Green Revolution,’’ argued that one answer
is to intensify agriculture to produce
more food on the same area of
land. But what he promoted as a policy
strategy, others have called the ‘‘Borlaug
hypothesis,’’ aiming to add it to sustainability
science theory and test it empirically.
In this issue of PNAS Rudel et al.
(2) follow earlier national studies (3) by
testing the hypothesis at global scale.
They demonstrate the existence of the
general phenomenon of ‘‘land sparing,’’
by showing that cropland area has increased
more slowly than population
since 1970. However, they find relatively
little evidence that intensification has
gone further, by shrinking cropland and
generating surplus ‘‘spared land,’’ and
much of this evidence is linked to
changes in trade patterns. Yet their article
will prove important for introducing
the concept of spared land into the literature,
inspiring more research, and stimulating
debate about how land sparing
relates to existing theory. This commentary
focuses on a key challenge they
identify (the measurement of land sparing)
and wider monitoring issues raised
by it. It refers mainly to developing
countries.